Evolution Theory PDF - LS.8.3.1

**EQ:** How do I explain the theory of evolution? LS.8.3.1 The theory of **[evolution]** states that life on Earth has changed over long periods of time and continues to change. Living things evolve in response to the changes in their environment. Charles Darwin is known as the \"Father of Evoluti...

**EQ:** How do I explain the theory of evolution? LS.8.3.1 The theory of **[evolution]** states that life on Earth has changed over long periods of time and continues to change. Living things evolve in response to the changes in their environment. Charles Darwin is known as the \"Father of Evolution.\" In the 1850s, he wrote an influential and controversial book called "**[On the Origin of Species]**.\" He proposed that ***all living things can trace their descent to a common ancestor***. This means that **every living organism on Earth, from the smallest bacteria to the largest whales, shares a single ancestral organism from which all life evolved over time, essentially making all living things distant relatives of one another.** **[Species]** is a group of similar organisms that can interbreed with each other to make healthy, fertile organisms. Charles Darwin set forth his ideas about evolution**.** These ideas were primarily based on observations from Darwin\'s travels around the globe. From 1831 to 1836, he was part of a survey expedition carried out by the ship **[HMS Beagle]**, which included stops in South America, Australia, and the southern tip of Africa. On each of the expedition\'s stops, Darwin had the opportunity to study and catalog the local plants and animals. Throughout his travels, Darwin began to see intriguing patterns in the distribution and features of organisms. In **Galápagos islands,** Darwin saw several different species of finch on each separate island. He noticed that each finch species had a different beak type, depending on the food available on its island. For example, the finches that ate large nuts had strong beaks for breaking the nuts open, while those that ate insects had thin, sharp beaks. Moreover, *he noted that each finch species was well-suited for its environment and role*. Therefore, he thought that each *finch species might have gradually adapted to local conditions* (over many generations and long periods of time) on each island. *This process could have led to the formation of one or more species on each island*. Darwin proposed that species can change over time. He believed that new species come from pre-existing species and that all species share a common ancestor. In this model, each species has its unique set of heritable (genetic) differences from the common ancestor, which accumulated gradually over very long periods. Darwin referred to this process, in which groups of organisms change in their heritable traits over generations, as \"descent with modification.\"